The R/C (abbreviation for “radio-controlled,” i.e., wireless-controlled) models are prevalent primarily for hobby use including: land vehicles such as four-wheeled vehicles or two-wheeled vehicles; gliding models such as airplanes or helicopters; water sailing models such as ships. A main body (a vehicle body of the four-wheel or two-wheeled vehicle, an airframe of the airplane, or a ship body of the ship) of such R/C models is mounted with an R/C receiver and a steering section having a steering actuator, wherein the steering section is driven by the steering actuator which moves according to the operation of the operation stick of the R/C transmitter by an operator allowing the main body of the running (flying, navigating) model to, for example, rotate.
The steering section of the two-wheeled vehicle generally consists of a steering shaft supported on a front part of a vehicle body (frame) with backward inclination at a predetermined caster angle, a front fork pivotally turning sideways around the steering shaft, a front wheel rotatably supported at the bottom end of the front fork, and the like. In the case of turning left from a straight driving position, by rotating the steering shaft to the right via a handle to turn the front wheel slightly to the right, inertia force tilts (rolls) the vehicle body to the left. From this condition, by turning the front wheel to the left to maintain the appropriate rolling angle, the vehicle will turn left at the turning radius determined by the rolling angle and the vehicle speed. In this way, the two-wheeled vehicle turns due to the rolling of the body caused by the steering part movement.
In a case that the steering shaft is pivotally connected, the righting moment is created by the front wheel alignment (such as the caster angle or the trail amount) when the torque applied to the steering shaft is eliminated, thereby recovering the posture of the vehicle body to the substantially upright position (the rolling angle is approximately 0°) making the vehicle travel straight. If a disturbance such as wind which tries to tilt the vehicle body is applied while traveling straight at a specific speed or higher, the alignment and gyro effect of the front wheel helps to maintain the vehicle body upright against the disturbance so as to maintain a straight traveling condition by autostabilizing the vehicle body as if riding a bicycle with no hands. Such a characteristic is referred to as “autostability.” Although even the model two-wheeled vehicle having reduced dimensions and shape of a full-scale vehicle can achieve rough autostability as long as the front wheel alignment is appropriate and the weight of the vehicle body (the main body of the model) is balanced, the gyro effect of the front wheel involving the dynamic stability is insufficient due to the inertia moment of the wheels being smaller compared to a full-scale vehicle and the caster effect involving the static stability (straight traveling performance) is also insufficient due to the inaccuracy of dimensions and vulnerability to the road surface condition.
Moreover, by supporting the steering shaft rotatably to ensure such mechanical autostability, there arises a problem wherein it becomes difficult to achieve the stable traveling condition when the front wheel vibrates due to disturbance by small projections, such as pebbles on the traveling surface, directly involving the front wheel steering angle.
As described above, for controlling the model two-wheeled vehicle remotely using the remote-controller, measures taken mechanically have been limited in relation to the above-described stability characteristic for the two-wheeled vehicle.
On the other hand, the technology related to the posture control of the R/C model two-wheeled vehicle is disclosed in, for example, Utility Model Registration Publication No. 2577593. In this prior art, there is provided an angular velocity sensor to detect the angular velocity of rotation (angular velocity of inclination) around a roll axis of the two-wheeled vehicle body along with the actuator (specifically, the servo motor) to alter the steering angle (direction angle) of the front wheel, so as to output the control signals to the actuator for controlling the angular velocity of inclination of the vehicle body to conform the actual steering angle of the front wheel to the angle (target value) received by the R/C receiver.
However, according to the prior art, while an operator can optionally determine the turning radius of the vehicle body by instructing the front wheel steering angle directly from the R/C transmitter, the traveling condition tends to be unstable due to the difficulty in control to balance the turning radius with the speed and the rolling angle.
For example, while only the turning radius in conjunction with the steering angle needs to be altered to maintain the predetermined rolling angle when the speed changes due to a disturbance while rolling, the rolling angle has to be altered as well to maintain the turning radius (which in conjunction with the steering angle). However, a vehicle body of large mass has to be displaced to alter the rolling angle, thereby causing slow reaction and difficulty in control.
Particularly, under a condition that the steering angle is small (the turning radius is large) when traveling at high speed, the deflection of the steering angle greatly affects the turning radius and thus the rolling angle in conjunction therewith, resulting in the instability of the vehicle body.
To solve the above-described problems of the prior art, the present inventor has carried out various studies regarding the control device of the R/C two-wheeled vehicle and, as a result, achieved the present invention from comprehension that stable posture control can be achieved by using the rolling angle of the model main body as a controlled variable instead of the steering angle of the steering section by complementing or replacing the above-described autostability with electrical control.
That is, an object of the present invention is to provide a rolling angle control device of an R/C traveling body such as an R/C model which facilitates the control of the vehicle body by an operator and to stabilize the posture of such as an R/C two-wheeled vehicle body in a wide speed range from low-speed to high-speed.